/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
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   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce::dsp
{

//==============================================================================
template <typename SampleType>
DryWetMixer<SampleType>::DryWetMixer()
    : DryWetMixer (0)
{
}

template <typename SampleType>
DryWetMixer<SampleType>::DryWetMixer (int maximumWetLatencyInSamplesIn)
    : dryDelayLine (maximumWetLatencyInSamplesIn),
      maximumWetLatencyInSamples (maximumWetLatencyInSamplesIn)
{
    dryDelayLine.setDelay (0);

    update();
    reset();
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::setMixingRule (MixingRule newRule)
{
    currentMixingRule = newRule;
    update();
}

template <typename SampleType>
void DryWetMixer<SampleType>::setWetMixProportion (SampleType newWetMixProportion)
{
    jassert (isPositiveAndNotGreaterThan (newWetMixProportion, 1.0));

    mix = jlimit (static_cast<SampleType> (0.0), static_cast<SampleType> (1.0), newWetMixProportion);
    update();
}

template <typename SampleType>
void DryWetMixer<SampleType>::setWetLatency (SampleType wetLatencySamples)
{
    dryDelayLine.setDelay (wetLatencySamples);
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::prepare (const ProcessSpec& spec)
{
    jassert (spec.sampleRate > 0);
    jassert (spec.numChannels > 0);

    sampleRate = spec.sampleRate;

    dryDelayLine.prepare (spec);
    bufferDry.setSize ((int) spec.numChannels, (int) spec.maximumBlockSize, false, false, true);

    update();
    reset();
}

template <typename SampleType>
void DryWetMixer<SampleType>::reset()
{
    dryVolume.reset (sampleRate, 0.05);
    wetVolume.reset (sampleRate, 0.05);

    dryDelayLine.reset();

    fifo = SingleThreadedAbstractFifo (nextPowerOfTwo (bufferDry.getNumSamples()));
    bufferDry.setSize (bufferDry.getNumChannels(), fifo.getSize(), false, false, true);
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::pushDrySamples (const AudioBlock<const SampleType> drySamples)
{
    jassert (drySamples.getNumChannels() <= (size_t) bufferDry.getNumChannels());
    jassert (drySamples.getNumSamples() <= (size_t) fifo.getRemainingSpace());

    auto offset = 0;

    for (const auto& range : fifo.write ((int) drySamples.getNumSamples()))
    {
        if (range.getLength() == 0)
            continue;

        auto block = AudioBlock<SampleType> (bufferDry).getSubsetChannelBlock (0, drySamples.getNumChannels())
                                                       .getSubBlock ((size_t) range.getStart(), (size_t) range.getLength());

        auto inputBlock = drySamples.getSubBlock ((size_t) offset, (size_t) range.getLength());

        if (maximumWetLatencyInSamples == 0)
            block.copyFrom (inputBlock);
        else
            dryDelayLine.process (ProcessContextNonReplacing<SampleType> (inputBlock, block));

        offset += range.getLength();
    }
}

template <typename SampleType>
void DryWetMixer<SampleType>::mixWetSamples (AudioBlock<SampleType> inOutBlock)
{
    inOutBlock.multiplyBy (wetVolume);

    jassert (inOutBlock.getNumSamples() <= (size_t) fifo.getNumReadable());

    auto offset = 0;

    for (const auto& range : fifo.read ((int) inOutBlock.getNumSamples()))
    {
        if (range.getLength() == 0)
            continue;

        auto block = AudioBlock<SampleType> (bufferDry).getSubsetChannelBlock (0, inOutBlock.getNumChannels())
                                                       .getSubBlock ((size_t) range.getStart(), (size_t) range.getLength());
        block.multiplyBy (dryVolume);
        inOutBlock.getSubBlock ((size_t) offset).add (block);

        offset += range.getLength();
    }
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::update()
{
    SampleType dryValue, wetValue;

    switch (currentMixingRule)
    {
        case MixingRule::balanced:
            dryValue = static_cast<SampleType> (2.0) * jmin (static_cast<SampleType> (0.5), static_cast<SampleType> (1.0) - mix);
            wetValue = static_cast<SampleType> (2.0) * jmin (static_cast<SampleType> (0.5), mix);
            break;

        case MixingRule::linear:
            dryValue = static_cast<SampleType> (1.0) - mix;
            wetValue = mix;
            break;

        case MixingRule::sin3dB:
            dryValue = static_cast<SampleType> (std::sin (0.5 * MathConstants<double>::pi * (1.0 - mix)));
            wetValue = static_cast<SampleType> (std::sin (0.5 * MathConstants<double>::pi * mix));
            break;

        case MixingRule::sin4p5dB:
            dryValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * (1.0 - mix)), 1.5));
            wetValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * mix), 1.5));
            break;

        case MixingRule::sin6dB:
            dryValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * (1.0 - mix)), 2.0));
            wetValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * mix), 2.0));
            break;

        case MixingRule::squareRoot3dB:
            dryValue = std::sqrt (static_cast<SampleType> (1.0) - mix);
            wetValue = std::sqrt (mix);
            break;

        case MixingRule::squareRoot4p5dB:
            dryValue = static_cast<SampleType> (std::pow (std::sqrt (1.0 - mix), 1.5));
            wetValue = static_cast<SampleType> (std::pow (std::sqrt (mix), 1.5));
            break;

        default:
            dryValue = jmin (static_cast<SampleType> (0.5), static_cast<SampleType> (1.0) - mix);
            wetValue = jmin (static_cast<SampleType> (0.5), mix);
            break;
    }

    dryVolume.setTargetValue (dryValue);
    wetVolume.setTargetValue (wetValue);
}

//==============================================================================
template class DryWetMixer<float>;
template class DryWetMixer<double>;


//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

struct DryWetMixerTests final : public UnitTest
{
    DryWetMixerTests() : UnitTest ("DryWetMixer", UnitTestCategories::dsp) {}

    enum class Kind { down, up };

    static auto getRampBuffer (ProcessSpec spec, Kind kind)
    {
        AudioBuffer<float> buffer ((int) spec.numChannels, (int) spec.maximumBlockSize);

        for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
        {
            for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
            {
                const auto ramp = kind == Kind::up ? sample : spec.maximumBlockSize - sample;

                buffer.setSample ((int) channel,
                                  (int) sample,
                                  jmap ((float) ramp, 0.0f, (float) spec.maximumBlockSize, 0.0f, 1.0f));
            }
        }

        return buffer;
    }

    void runTest() override
    {
        constexpr ProcessSpec spec { 44100.0, 512, 2 };
        constexpr auto numBlocks = 5;

        const auto wetBuffer = getRampBuffer (spec, Kind::up);
        const auto dryBuffer = getRampBuffer (spec, Kind::down);

        for (auto maxLatency : { 0, 100, 200, 512 })
        {
            beginTest ("Mixer can push multiple small buffers");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push samples one-by-one
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                        mixer.pushDrySamples (AudioBlock<const float> (dryBuffer).getSubBlock (sample, 1));

                    // Mix wet samples in one go
                    auto outputBlock = wetBuffer;
                    mixer.mixWetSamples ({ outputBlock });

                    // The output block should contain the wet and dry samples averaged
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, (int) sample);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }

            beginTest ("Mixer can pop multiple small buffers");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push samples in one go
                    mixer.pushDrySamples ({ dryBuffer });

                    // Process wet samples one-by-one
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        AudioBuffer<float> outputBlock ((int) spec.numChannels, 1);
                        AudioBlock<const float> (wetBuffer).getSubBlock (sample, 1).copyTo (outputBlock);
                        mixer.mixWetSamples ({ outputBlock });

                        // The output block should contain the wet and dry samples averaged
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, 0);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }

            beginTest ("Mixer can push and pop multiple small buffers");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push dry samples and process wet samples one-by-one
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        mixer.pushDrySamples (AudioBlock<const float> (dryBuffer).getSubBlock (sample, 1));

                        AudioBuffer<float> outputBlock ((int) spec.numChannels, 1);
                        AudioBlock<const float> (wetBuffer).getSubBlock (sample, 1).copyTo (outputBlock);
                        mixer.mixWetSamples ({ outputBlock });

                        // The output block should contain the wet and dry samples averaged
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, 0);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }

            beginTest ("Mixer can push and pop full-sized blocks after encountering a shorter block");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                constexpr auto shortBlockLength = spec.maximumBlockSize / 2;
                AudioBuffer<float> shortBlock (spec.numChannels, shortBlockLength);
                mixer.pushDrySamples (AudioBlock<const float> (dryBuffer).getSubBlock (shortBlockLength));
                mixer.mixWetSamples ({ shortBlock });

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push a full block of dry samples
                    mixer.pushDrySamples ({ dryBuffer });

                    // Mix a full block of wet samples
                    auto outputBlock = wetBuffer;
                    mixer.mixWetSamples ({ outputBlock });

                    // The output block should contain the wet and dry samples averaged
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, (int) sample);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }
        }
    }
};

static const DryWetMixerTests dryWetMixerTests;

#endif

} // namespace juce::dsp
